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Operation
Operator's responsibilities
It is important that the operator is appropriately trained and becomes familiar with the system before operating the
machine. In addition to reading this manual, the operator must study the microprocessor operating manual and the wiring
diagram in order to understand startup sequence, operation, shutdown sequence and operation of all the safety devices.
During the machine's initial startup phase, a technician authorized by the manufacturer is available to answer any
questions and to give instructions as to the correct operating procedures.
The operator is advised to keep a record of operating data for every installed machine. Another record should also be
kept of all the periodical maintenance and servicing activities.
If the operator notes abnormal or unusual operating conditions, he is advised to consult the technical service authorized
by the manufacturer.
Description of the machine
This machine, of the water condensation type, is made up of the following main components:
Compressor:
Evaporator:
Condenser:
Expansion valve:
Description of the refrigeration cycle
The lowtemperature refrigerant gas from the evaporator is drawn by the compressor through the electric motor, which is
cooled by the refrigerant. It is subsequently compressed and during this process the refrigerant mixes with the oil from
the oil separator.
The highpressure oilrefrigerant mixture is introduced into the centrifugetype highefficiency oil separator, where the oil is
separated from the refrigerant. The oil accumulated on the bottom of the separator is forced by the pressure difference
back into the compressor while the oilfree refrigerant is sent to the condenser.
The refrigerant fluid is evenly distributed inside the condenser throughout the volume of the exchanger, and the gas in
contact with the tubes is cooled and successively starts to condense.
The condensed fluid at saturation temperature passes through the subcooling section where it looses even more heat,
increasing the efficiency of the cycle. The heat taken from the fluid during cooling, condensation and subcooling is
exchanged with that of the water passing inside the condenser tubes.
The subcooled fluid flows through the highefficiency filter dryer and then reaches the expansion element (expansion
valve) through which a fall in pressure starts off the expansion process resulting in the vaporisation of part of the
refrigerant liquid.
The result at this point is a lowpressure and lowtemperature liquidgas mixture entering the evaporator, where it takes the
heat required for vaporisation.
When the refrigerant liquidvapour is uniformly distributed in the direct expansion evaporator tubes, heat is exch anged
with the cooling water, thus reducing the temperature until complete evaporation, followed by superheating.
Once it has reached the superheatedvapour state, the refrigerant leaves the evaporator and is once again taken into the
compressor to repeat the cycle.
D-EIMWC00208-16EN - 20/48
The singlescrew compressor of the Fr 3200 series is of the semihermetic type and
utilises gas from the evaporator to cool the motor and allow optimal operation under any
expected load conditions. The oilinjection lubrication system does not require an oil
pump as oil flow is ensured by the pressure difference between delivery and suction. In
addition to ensuring lubrication of ball bearings, oil injection dynamically seals the screw,
thus enabling the compression process.
The directexpansion shell and tube type evaporator is of ample size in order to ensure
optimum efficiency under all load conditions.
The shell and tube type condenser has external high efficiency micro fins (C4).
The liquid subcooled by the lower part of the tubes not only improves overall efficiency of
the machine but also compensates variations in heat load by adapting the refrigerant
load to all foreseen operating conditions.
The machine has a an electronic expansion valve, which is controlled by an electronic
device called a Driver that optimises its operation.
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